Power of Attorney

        Know all by these presents that the undersigned does hereby make,
constitute and appoint each of Karen M. McCarthy and Larry Miller, or any one of
them, as a true and lawful attorney-in-fact and agent of the undersigned, with
full powers of substitution and revocation, for and in the name, place and stead
of the undersigned (in the undersigned's individual capacity), to execute and
deliver such forms that the undersigned may be required to file with the U.S.
Securities and Exchange Commission as a result of the undersigned's ownership of
or transactions in securities of Blue Buffalo Pet Products, Inc. (i) pursuant to
Section 16(a) of the Securities Exchange Act of 1934, as amended, including
without limitation, statements on Form 3, Form 4 and Form 5 (including any
amendments thereto), and (ii) in connection with any applications for EDGAR
access codes or any other documents necessary or appropriate to obtain codes and
passwords enabling the undersigned to make electronic filings with the
Securities and Exchange Commission, including without limitation the Form ID.
This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with regard to the
undersigned's ownership of or transactions in securities of Blue Buffalo Pet
Products, Inc., unless earlier revoked in writing. The undersigned acknowledges
that Karen M. McCarthy and Larry Miller are not assuming any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.

                                        By:    /s/ Michael Nathenson
                                               ---------------------------------
                                               Michael Nathenson

                                        Date:  July 8, 2015
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